This invention relates in general to a coupling which is adapted to be crimped to an end of a flexible pressure hose and in particular, to a unique metal collar, which forms part of the coupling, and is adapted to be crimped over the end of a pressure hose.
Pressure hose couplings are used in many places to connect flexible pressure hoses to moveable machinery parts. Such hoses transmit hydraulic fluids or compressed air under high pressure between such components as pumps, valves, and hydraulic actuators. The flexibility of the hose permits relative movement between such devices.
One example of a prior art hose coupling and the associated metal collar is shown in FIGS. 1, 2 and 3. Referring first to FIG. 3, there is shown a prior art pressure hose coupling, generally indicated by the reference number 10, which has been secured to one end of a flexible pressure hose 11. The coupling 10 includes a nipple 12 and a metal collar 13, with the collar 13 being coaxially positioned around one end of the nipple, and being crimped to an intermediate portion 14 of the nipple 12. The collar 13 and one end 15 of the nipple 12 cooperate to form an annular space into which the flexible hose end 11 is inserted. Once inserted, the outer surface of the nipple end 15, which is typically provided with a series of annular teeth, will sealingly engage the inner surface of the hose end. The opposite end of the nipple 12 can have external threads 16 as shown in FIG. 3, or with other means for attachment to an associated connection point.
The particular collar 13 which forms part of the hose coupling shown in FIG. 3 is shown in more detail in FIGS. 1 and 2. As shown in FIG. 2, the collar is provided with a series of axially spaced apart annular grooves 17 formed on an inner surface thereof which, when crimped about the associated hoses, securely grip the outer surface of the hose to securely attach the hose to the coupling. It has been found that, in high pressure applications, it is necessary to provide the annular grooves with generally flat surface portions 18 to prevent the hose from being disconnected from the coupling. The grooves 17 shown in the metal collar 13 of FIGS. 1 and 2 are typically formed by a machining operations, such as on a screw or lathe machine. As can be appreciated, the machine operation is a relatively time consuming and expensive operation, and requires that the metal tube have a sufficient wall thickness to accommodate the grooves.
An alternate method of forming metal collars for hose couplings is disclosed in U.S. Pat. No. 4,691,550. In this patent, the interior grooves of the above described collar are replaced by raised annular beads that are individually formed on the interior of a cylindrical metal sleeve by a pressing operation. The pressing operation can be either roll forming, in which case the beads are continuous, or by a collapsible segmented die, in which case the beads will include circumferential interruptions. After each bead is formed, a stamping die is inserted into the sleeve and impressed against the the bead to form a continuous annular toothed gripping surface thereon. While this process enables a thinner walled sleeve to be used, a separate pressing and then stamping operation is required to individually form each internal bead.